This invention relates to a pulse signal generator. This invention also relates to a redundancy selection signal generator.
It is good that semiconductor devices such as semiconductor memories can operate in a wide range of a power supply voltage. In some cases, pulse signal generators are used to control semiconductor devices. As will be explained later, a prior art pulse signal generator has some problem.
During the fabrication of semiconductor memories, there is a chance that one or more memory cells go defective. Some semiconductor memories feature a redundancy, including ordinary memory cells and redundant or spare memory cells. When an ordinary memory cell goes defective, the defective memory cell is replaced by a redundant memory cell. This replacement is executed in response to the output signal from a redundancy selection signal generator. As will be explained later, a prior art redundancy selection signal generator has some problems.